1. Field of the Invention
Methods consistent with the present invention relate to transferring a rights object (RO) and an electronic device, and more particularly, to transferring an RO and an electronic device which can prevent an RO from being copied during the transfer of the RO.
2. Description of the Related Art
In recent years, research has been vigorously conducted on Digital Rights Management (DRM), which is a technology for protecting digital content that can be easily copied and distributed, and various services adopting DRM technology have been or are currently being commercialized.
Related art techniques of protecting digital content generally focus on the prevention of illegitimate access to digital content. For example, in the related art, only users who have paid charges for digital content are allowed to access the digital content, whereas users who have not paid any charges for the digital content are not allowed to access the digital content.
Due to the characteristics of digital data, digital content can be easily reused, processed, copied, and distributed. Therefore, if digital content is illegitimately copied or distributed by users who have access to the digital content, the digital content can be used even by users who have not paid any charges for the digital content and are thus not eligible for the digital content.
In order to address this, DRM technology requires encryption of digital content for safe distribution of digital content and also requires a predetermined license, called a Rights Object (RO), for the use of digital content.
Referring to FIG. 1, a user who wishes to use digital content may be provided with desired digital content by a content provider 120 with a host device 110. The digital content provided by the content provider 120 is encrypted. In order to use encrypted digital content (hereinafter referred to as a content item), an RO is necessary.
The user may purchase an RO including the right to execute a content item from an RO issuer 130 using the host device 110. The right to execute the content item may be a content encryption key that is necessary to decrypt the content item.
The RO issuer 130 may report a statement regarding the issuance of ROs to the content provider 120. The RO issuer 130 may be the same entity as the content provider 120.
A user can use a content item by acquiring an RO corresponding to the content item.
A content item can be freely copied to or distributed to a number of users without an RO. An RO includes usage restriction information regarding the number of times that a content item can be used, a period of time for which the content item can be used, and/or the number of times that the RO can be copied, and thus imposes restrictions on the reuse or copy of content.
In short, it is possible to effectively protect digital content using DRM technology
A user may store an RO in a host device such as a mobile phone or a personal digital assistant (PDA) which can execute multimedia data.
In order to facilitate the maintenance and distribution of content items and ROs, methods of storing ROs in portable storage devices such as memory sticks or multimedia cards (MMCs) have been developed.
FIG. 2 illustrates a flowchart of a related art method of transferring an RO present in a host device 110 to a portable storage device 140. When the portable storage device 140 is connected to the host device 110, a user can execute an RO transfer command for transferring an RO from the host device 110 to the portable storage device 140.
Referring to FIG. 2, in operation S110, the host device 110 transfers an RO to the portable storage device 140 upon execution of an RO transfer command. In operation S120, when the transfer of the RO is complete, the portable storage device 140 notifies the host device 110 of the completion of the RO transfer. In operation S130, the host device 110 removes the RO present therein upon being notified that the transfer of the RO has been completed.
If the method is terminated abnormally at a time A between operation S110 and operation S120, the host device 110 cannot be notified of whether the transfer of the RO has been completed and thus may not be able to decide when to remove the RO present therein. As a result, the RO remains in both the host device 110 and the portable storage device 140. That is, the RO is copied during the transfer of the RO.